A known practice from U.S. Pat. No. 5,783,265 is the production of sealed registration signs made of plastic material for vehicles. Such signs have been found to be very advantageous.
A known practice from U.S. Pat. No. 6,025,784 is registration signs for vehicles being provided with transponders for reception and/or transmission of radio signals.
Transponders can contain information of various kinds, e.g. information about the vehicle's registration number, chassis number, make etc. The information is read by means of suitable equipment, e.g. on or beside the carriageway. It is thus possible to compare information which appears on a vehicle's signs with information in the vehicle register, i.e. to check that the signs pertain to the correct vehicle. Information obtained can also be used for many other purposes, e.g. for traffic audit, travelling time audit, running times, running speeds and for various kinds of neutral statistics.
However, the first-mentioned registration signs are not designed to allow the use of transponders for reception and/or transmission of radio signals via them, nor to allow rapid and sealed association with transponders to them.